Entries in Narrow FM
(1)

While recently riding in the mountains of North Carolina with a small group of GMRS radio equipped riders, one of the riders commented that my audio was a lot "lower" than that of fellow rider Ed Gray. Ed has the exact same Autocom intercom (Active 7 Smart) and GMRS radio (IC-F21GM). This got me thinking again. I hate it when that happens.

I was already "eating" the microphone in my helmet, so that didn't seem to point to the low audio problem and I know from Elizabeth's POV that she hears me loud and clear from the pillion. The Autocom doesn't have any user-adjustable controls for transmit audio, nor does the ICOM radio. However, I did begin to wonder about the FM Mode selection button on the radio. By default, these radios are all supposed to be set to FM Narrow, which takes up less radio spectrum every time you transmit. FM Wide is also an option and effectively adds a bit of punch to your signal.

Pressing and holding the Wide/Narrow button ensures that radio is in FM Narrow mode. I felt pretty certain that I was going by the book and using Narrow, so I tried a little test.

With the radio removed from the bike, rubber antenna and battery installed, I enlisted the help of a scanning receiver and headphones so that I could listen to myself when transmitting.

With the radio in FM Narrow mode, I was able to hear myself, but the audio lacked life. I pressed the Wide/Narrow button once (didn't hold it) which changes the mode to FM Wide. I repeated the test, but oh what a difference. The audio was substantially louder and easier to copy.

I'm going to leave my radio in FM Wide mode for future rides and ask for some comparison to Ed's audio. If Ed's willing, I also intend to run a little test with his radio, comparing his transmit audio as it is right now (no button pressing) to what it sounds like after a single press of the Wide/Narrow button (without holding). I'm expecting no change in audio, which will confirm that he's been running his radio in FM Wide mode.

Then, I guess the next question is whether there's anything wrong from the FCC's POV in running these radios in wide mode. More later.